Factors predicting weight-bearing asymmetry 1 month after unilateral total knee arthroplasty: A cross-sectional study

Factors predicting weight-bearing asymmetry (WBA) after unilateral total knee arthroplasty (TKA) are not known. However, identifying modifiable and non-modifiable predictors of WBA is needed to optimize rehabilitation, especially since WBA is negatively correlated to poor functional performance. The purpose of this study was to identify factors predictive of WBA during sit-stand transitions for people 1 month following unilateral TKA. Methods: Fifty-nine people were tested preoperatively and 1 month following unilateral TKA for WBA using average vertical ground reaction force under each foot during the Five Times Sit-to-Stand Test. Candidate variables tested in the regression analysis represented physical impairments (strength, muscle activation, pain, and motion), demographics, anthropometrics, and movement compensations. Results: WBA, measured as the ratio of surgical/non-surgical limb vertical ground reaction force, was 0.69 (0.18) (mean (SD)) 1 month after TKA. Regression analysis identified preoperative WBA (beta = 0.40), quadriceps strength ratio (beta = 0.31), and hamstrings strength ratio (beta = 0.19) as factors predictive of WBA 1 month after TKA (R-2 = 0.30). Conclusion: Greater amounts of WBA 1 month after TKA are predicted by modifiable factors including habitual movement pattern and asymmetry in quadriceps and hamstrings strength. (C) 2012 Elsevier B.V. All rights reserved.